Abstract
IN the mode of fracture at elevated temperatures and low stresses which involves the nucleation and growth of voids on grain boundaries1, the initial stage of formation of the voids is generally considered to depend on a mechanism whereby close competition takes place between the rate of separation of interfaces and the simultaneous tendency to closure by sintering processes. If a void can be opened to a critical size, which depends on the stress and surface tension of the material, then its continued growth can be accounted for by vacancy condensation2, but there is little information about the important parameters which may govern conditions before this stage is reached. Proposed mechanisms for void nucleation usually envisage that the most favourable circumstances for nucleation arise when the deformation, particularly the contribution due to grain boundary sliding, is rapid. In such cases it is often considered the void has a higher probability of opening sufficiently before a competing sintering process can be effective in preventing the critical size being reached3. This letter presents initial results on experiments with the specific aim of determining the variation of nucleation rate with the rate of deformation.
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RATCLIFFE, R., GREENWOOD, G. Formation of Voids in Creep and Competition from Sintering Processes. Nature 215, 50 (1967). https://doi.org/10.1038/215050a0
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DOI: https://doi.org/10.1038/215050a0
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